The present invention relates to direct current (“DC”) pre-erasing servo channels of a magnetic tape prior to writing servo data in a servo channel. The present invention particularly relates to those servo recordings which were written with a uni-polar current waveform. The DC pre-erase is performed using a uni-polar direct current of a polarity that is opposite to the polarity of the direct current used to write the servo data. This pre-erase may be done with one or more heads. Also, as will be described, the pre-erase of a servo channel and writing to a servo channel may be done by making two passes over a single head or by using two or more heads to perform both steps. Also, it is within the scope of the present invention to have the heads mounted on a single mount or have the heads on separate mounts and on separate tape decks.
Legal claims defining the scope of protection, as filed with the USPTO.
1. Magnetic tape comprising a substrate and a magnetic layer, the magnetic tape having at least one direct current pre-erased servo track that includes servo data and at least one alternating current pre-erased data track for receiving data subsequently written thereon.
2. The magnetic tape of claim 1 , wherein the servo data is time-based.
3. The magnetic tape of claim 1 , wherein the servo data is amplitude based.
4. The magnetic tape of claim 1 , wherein the servo data is a combination of time-based and amplitude based servo data.
5. The magnetic tape of claim 1 , wherein the direct current pre-erased servo channel provides a greater input signal than one that is not direct current pre-erased.
6. A magnetic tape having at least one servo channel that is direct current pre-erased and has servo data written in the at least one servo channel and at least one alternating current pre-erased data channel for receiving data subsequently written thereon, the magnetic tape made by a method comprising: writing a servo pattern using a unipolar direct current; prior to the act of writing a servo pattern, erasing at least one servo channel of the magnetic tape by applying a direct current of a substantially opposite polarity of the servo write current.
7. The magnetic tape of claim 6 , wherein the act of writing and erasing is performed using a first head.
8. The magnetic tape of claim 7 , wherein the act of writing and erasing is performed using a first head further comprising providing a head with a time-based servo pattern.
9. The magnetic tape of claim 7 , wherein the act of writing and erasing is performed using a first head further comprising providing a head with an amplitude-based servo pattern.
10. The magnetic tape of claim 7 , wherein the act of erasing at least one servo channel of the magnetic tape is performed by first passing a portion of the magnetic tape that includes the at least one servo channel to be erased over the first head.
11. The magnetic tape of claim 10 , wherein the act of writing a servo pattern in the at least one servo channel of the magnetic tape is performed by then passing a portion of the magnetic tape that includes the at least one servo channel to be written over the first head.
12. The magnetic tape of claim 6 , wherein the act of erasing and writing are performed using two heads.
13. The magnetic tape of claim 12 , wherein the act of erasing is performed by a first head and the act of writing a servo pattern is performed by a second head.
14. The magnetic tape of claim 13 , wherein the act of erasing by use of a first head, further comprises using a first head that includes a time based servo pattern.
15. The magnetic tape of claim 13 , wherein the act of erasing by use of a first head, further comprises using a first head that includes an amplitude-based servo pattern.
16. The magnetic tape of claim 13 , wherein the act of erasing by use of a first head, further comprises using a first head that includes an erase pattern having a erase gap track width that is substantially the same as the servo gap track width.
17. The magnetic tape of claim 13 , wherein the act of erasing by use of a first head, further comprises providing a first head that is one of a thin film head, ferrite based head, and surface thin film head.
18. The magnetic tape of claim 13 , wherein the act of erasing by use of a first head, further comprises providing a first head that is a ferrite MIG type head.
19. The magnetic tape of claim 13 , wherein the act of writing by use of a second head, further comprises providing a second head that is one of a thin film head, ferrite based head, and surface thin film head.
20. The magnetic tape of claim 19 , wherein the act of writing further comprises writing at least one of an amplitude-based and timing-based servo pattern.
21. The magnetic tape of claim 12 , wherein the two heads are located on a single mount.
22. The magnetic tape of claim 12 , wherein the heads are located on separate mounts.
23. The magnetic tape of claim 12 , wherein the head used to erase is located on a separate tape deck from the head used to write a servo pattern.
24. An apparatus for use in pre-erasing magnetic tape, comprising: a housing supporting at least one head, wherein at least one head includes a pattern to direct current pre-erase at least one servo channel on the magnetic tape without direct current pre-erasing data channels on the magnetic tape.
25. The apparatus of claim 24 , wherein the heads are thin film heads.
26. The apparatus of claim 24 , wherein one head is a surface thin film head and another head is a low inductance surface thin film head.
27. The apparatus of claim 24 , wherein the at least one head comprises at least two heads, and at least one of the two heads is a ferrite MIG head.
28. The apparatus of claims 25 , 26 , or 27 , wherein at least one head includes a pattern used to erase each servo channel of the magnetic tape.
29. The apparatus of claim 24 , wherein the housing supports at least two heads, wherein at least one of the heads is used to direct current, pre-erase at least one servo channel of the magnetic tape.
30. The apparatus of claim 29 , wherein the pre-erase head is a ferrite based head.
31. The apparatus of claim 29 , wherein at least one of the heads is used for writing a servo pattern and is selected from one of a thin film head, ferrite based head, and surface thin film head.
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January 30, 2004
October 16, 2007
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